1. Technical Field
This invention relates to diapers especially for infants, but also for incontinence protection and napkins and more in details to the type of diapers including at least one at least partly moisture tight enclosing layer and one or more inner layers having a good absorption ability.
2. Description of the Prior Art
There are known different ways of controlling the absorption of liquid in the absorbing layer.
SE 400 459 discloses a disposable diaper wherein an absorbing layer is provided with a number of through openings. The absorbing layer is freely arranged relating to a tight rear or outside layer and is covered by a moisture permeable inner or forward layer. The idea with this is that moisture will be able to pass through the inner layer simultaneously as it is partly absorbed, pass through the through openings towards the rear of the absorbing layer in order to, aided by the tight outside layer, be distributed or spread over the absorbing layer.
DE3 426 897 discloses another solution of a similar kind. It includes a tight outer or rear layer, an absorbing filling and an inner layer and also in this case the absorbing layer is provided with one or more through openings. The inwardly facing covering layer is double and includes a first tight layer having holes corresponding to those of the absorbing layer and an outer layer of non-woven material. The intention hereby is to gain the advantage that liquid can be spread on the non-woven woven material in order to eventually reach the position of any of the openings and pass through the non-woven material and through any of the holes in the tight foil layer to reach the openings of the absorbing layer so that the moisture can be absorbed essentially through the edges of the latter openings.
Common features of the known constructions are that they, in spite of the increase of the absorption area by the holes or openings provided and the passages arranged at the inner layer, are unable to take care in a desired and intended way, of concentrated volumes of liquid within a limited area, the result being that the liquid is distributed over the entire inside of the diaper and easily leaks out at the edges. It also occurs that liquid in free state fills one or any of the openings of the absorbing layer and to oversaturation fills the adjoining absorption material portions whereas the rest of the absorbing layer is unutilized and only eventually will take in the absorption. Local oversaturation of the absorbing layer will result in leak risks back towards the carrier or laterally at the edges.
It has been established that, in known constructions, the absorbing ability of the absorbing material is poorly taken advantage of. An estimation discloses that only about half of the material is used which means that half of it is disposed of unused. One reason behind the faulty effect seems to be that once the material absorbs liquid, it has a tendency to compact and form clods and this prevents the liquid from spreading. One reason behind this tendency to form lumps or clods is that the material consists of long and short fibers. The movements of the user result in separation of the fiber material so that the continuous layer or body of fiber material disintegrates into smaller gatherings or lumps of fibers. The gaps or cracks formed between the separate gatherings or lumps make the intended distribution of liquid over the entire absorbing layer or body impossible, which results in local oversaturation and leaking in spite of the fact that only a fraction of the capacity of the material has been taken advantage of.